 It can mediate exotic processes such as V+A muon decay and muonium-antimuonium conversion.It can also give rise to exotic scattering processes such as electron plus electron goes to muon plus muon which is forbidden in the Standard Model.Detailed measurements made at the Paul Scherrer Institute (PSI) have searched for the exotic muon decay and placed a lower bound on the bilepton mass of about 1 TeV.